Undressed lumber and process of preserving same.



UNITED STATES .Patented December 15, 1903.

PATENT Cur-ion.

GEORGEC. COWLES, OF BAY MILLS, MICHIGAN, ASSIGNOR TO ROBERT H.

MUNSON, OF BAY MILLS, MICHIGAN.

UNDRESSED LUMBER AND PROCESS OF PRESERVING SAME.

SPECIFICATION forming part of Letters Patent No. 746,678 dated December15, 1903. Application filed July 11, 1-902. Serial No. 115,224. (Nospecimens.)

To aZZ whom it may concern:

Be it known that I, GEORGE C. OowLEs, a citizen of the United States,residing at Bay Mills, in the county of Bay Mills and State of Michigan,have invented a new and useful Lumber and Process of Producing the Same,of which the following is a specification.

This. invention relates to a novel process of treating wood to preventsap-staining and to the product of the process.

- At certain seasons of the year, particularly during the summer months,green lumber rapidly deteriorates in market value by reason of what isknown as sap-mold, which commences to form almost as soon as the boardleaves the saw and gradually penetrates the board from the surfacethereof, producing black and blue stains, which prevent the sale of thestock as clear lumber, and therefore greatly reduce its value.

The object of my present invention, therefore, is to devise aninexpensive and effective process for treating green or undressed lumberto prevent sap-staining, and to thereby produce lumber which may beexposed indefinitely to the open air without danger of deteriorationfrom such cause.

To this end the process consists in subjecting the wood to a surfacetreatment with a neutralizing agent to prevent the formation of surfacemold and afiecting only that portion or surface depth of the lumberwhich is planed 01f when the stock is dressed. The result of thistreatment is the prevention of sap-stains and the removal of allevidences of the treatment by the dressing of'the lumber, the dressedstock being left perfectly clear and of standard color and strength.

In practicing the process the undressed board to be treated is dipped inan alkaline solution, preferablya five-per-cent. solution of bicarbonateof soda, to efiect the surface treatment of the board with aneutralizing agent. The immersion of the board in the solution is asbrief as possible, a fraction of a second being sufficient to cause theneutralization of the acetic acid in the surface of the wood. By thismeans the surface only of the wood is affected by the chemical, andfermentation and the consequent formation of the sap-mold areeffectually arrested or prevented by the neutralization of that portionof the acid which is exposed to the air. It is of course understood thatthe mold which produces the objectionable stains is due to thefermentation of the acetic acid, as the latter is oxidized when drawn tothe surface of the board by the flowing of the sap in consequence ofcertain. atmospheric conditions. It follows, therefore, that theimpregnation of the surface only of the lumber will neutralize the acidin the sap, which would otherwise ferment under the oxidizing influenceof the atmosphere and produce the mold and its accompanying stain. Asthe initial fermentation is prevented at the surface of the board, itnecessarily follows that the interior of the board will not be stainedand will not be impregnated with orin any wayafl'ected by theneutralizing agent with which the surface only of the board is treated.After the stock has been dipped in the alkaline solution in the mannerdescribed it is stored in any'suitable manner and either air or kilndried. The drying of the stock in the condition in which it comes fromthe alkaline bath is a material step of the process, because the removalof all traces of the alkali-.-as, for instance, by washing-would inlarge measure, if not wholly, destroy the practical effect of theimmersion, and the stock would be liable to subsequent staining. As aresult of the rapid immersion or dipping of the stock in the alkalinebath and the subsequent drying of the stock its thin surface portion,which is planed OK when the stock is dressed, becomes a protective skin,the pores of which are closed by neutralized sap and microscopicdeposits of the neutralizing agent. The color of this protective skin orsurface layer will be nearly, if not absolutely, natural, and

when said layer is planed off in dressing the lumber the protected stockwill be found to be sound, bright, and unstained and absolutelyunadected by the treatment which has prevented its deterioration.

It will therefore appear that my novel process consistsin impregnatingthe surface of undressed lumber with an alkaline (preferablybicarbonate-of-soda) solution to such depth only as will insure thetotal removal of the impregnated surface when the lumber is dressed. Ihave stated that a solution of hicarbonate of soda is thought to bepreferable for the treatment of stock in the manner described. This isfor the reason that bicarbonate of'soda is almost perfectly soluble inofan alkali, the strength of the solution depending, of course, upon thealkaline activity of the chemical used. Certain of the abovementionedcompounds besides being comparatively expensive will leave a crystallinedeposit on the stock, which renders it comparatively unmarketable, whilecertain others-as, for instance, the compounds of ammoniaare toovolatile, and therefore,un1ess properly confined, will vaporize beforethe stock has received the proper treatment. As stated, however, thesecompounds are all available, although the compounds of soda (andparticularly the carbonate and bicarbonate of soda) are preferable,because they are inexpensive and do not materially discolor the lumberor leave a crystalline deposit upon the surface thereof.

It is appreciated that rapidly dipping the undressed wood in a weakalkaline solution is one of the several ways in which the rapidapplication of the said solution may be offected in accordance with theinvention, and it is to be understood, therefore, that the inventionembraces within its'scope any manipulation which will result inefiectiug the rapid application of the solution to the wood in a mannerwhich will produce the desired protective surface or skin withoutappreciably afiecting the structure lying within the confines thereof.

What I claim is- 1. That process of treating undressed lumber to preventsap-staining thereof, which consists in rapidly applying to the wood aweak alkaline solution to permit said solution to penetrate only thatsurface depth which is planed olf by the usual dressing of the wood.

2. That process of treating undressed lumber to prevent sap-stainingthereof, which consists in rapidly dipping the wood into a weak solutionof sodium bicarbonate, to permit said solution to penetrate only thatsurface depth which is plaued off by the usual dressing of the wood.

3. That process of treating undressed lumber to prevent sap-stainingthereof, which consists first in rapidly dipping the wood into a weaksolution of sodium bicarbonate, to permit said solution to penetrateonly that surface depth which is planed off by the usual dressing of thewood, and second in drying the lumber so treated.

4. As a new article of manufacture, an undressed board having aprotectiveskin or su rface layer formed of neutralized sap and theneutralizing agent, said skin or surface layer being of a depth whichwill enable it to be planed off by the usual dressing of the board.

In testimony that I claim the foregoing as my own I have hereto afiixedmy signature in the presence of two witnesses.

' GEO. O. COWLES.

Witnesses:

L. E. PERRY, W. KENNELLY.

